Member postings for Martin Shaw 1

I have a need to tap some M8 holes. From published information it seems the tapping drill can be anything from 6.8mm to 7.5mm. I appreciate the small drill will produce a tight thread and the large one a loose fit, so is approximately the mid point between the sizes the optimum, given that the application is some T nuts. I would appreciate your thoughts.

Regards

Martin

Just for the record, the earth loop impedance of a given supply, at the supply point (the meter) should be no greater than 0.8R for a TNS supply and no greater than 0.35R for a TNCS supply. It can be and often is lower, the princpal variant being the distance from the substation.

Brian G makes a very valid point, the house previous to my current one was built in 1922 and used the lead rising main as the earth electrode which was fine until the supply pipe was replaced by an MDPE one. It took 18 months to persuade the DNO to provide an earth which took 5 minutes to implement. It's certainly worth checking in an older property that there is an earth at all.

I would agree with Emgee that a separate supply to the workshop is sensible, not least because you not limiting the current availability to the rating of the circuit it is currently spurred from and as in this case a ground floor ring final might well have a washing machine, dishwasher, tumble dryer all potentially in use at the same time before considering the workshop needs. If it can be done easily I would.

Regards

Martin

I suppose it depends on whether you call old Scots a regional dialect or not, I'm in the not camp for self preservation reasons. Clead is an old Scots word meaning clothes/ clothing hence boiler cleading or boiler clothing. I feel cladding really only applies to sheet steel mounted in crinolines, no doubt there are many equally valid explanations.

Regards

Martin

There's currently a chap in the wanted ads looking for a Myford on a stand, got to be worth a conversation.

Martin

James

I'm near Glasgow and I have a Sieg SC3 supplied by Arc. If you can face the west your more than welcome to visit my workshop and have a look and play, and get my feedback. PM me if you want to take it further.

Kind regards

Martin

Thanks Jason, I'll give it a try tomorrow.

Regards

Martin

Arc delivered to me a 2.5" flycutter and a pre ground HSS cutter, so thought I should try it out. Obviously never having used one before I didn't expect perfection however as you can see from the pic it is several hundred percent better than the first effort. I cut at 570rpm, a doc of 20 thou, and a fairly conservative feed rate, and whilst it's not glass and the tool marks are feelable it would suffice if surface finish wasn't critical, it isn't. I will do the other side at a slightly faster rpm to see whether that finesses the finish.The chips were definitely hot and tending towards blue, does this indicate the feed rate is still too high? A huge step forward nonetheless.

Regards

Martin

Firstly my thanks to David for his kind and generous offer, and to both Jason and Ron for the additional information. I have decided to order from Arc a fly cutter, I know in the spirit of things I should make it, however by the time I've trolled around gathering materials etc and time which does have a cost if not directly financial, I will have spent at least as much. Once I have received it and had a go I'll report success or otherwise.

Many thanks

Martin

Edited By Martin Shaw 1 on 09/05/2019 11:19:58

Thanks guys, I think tomorrow I will try again with a new 4 flute cutter, up the revs and see if I can work out the feed rate that will give me the correct chip load. I'll let you all see the outcome. I think one of the learning curves beginners have is an acceptance that cutters are consumables and don't last for ever.

Regards

Martin

Right, in answer to some questions I was cutting at 400rpm, which appears to be too slow, and with a v small DOC just to see what the finish was like. I have put a pic below, pretty it ain't, and I do wonder whether the cutter is a bit blunt. There are distinct ridges between the passes which certainly shouldn't be there. I have never used either a fly cutter or a face mill so I'm well in the dark, but from Jason's comment it seems a fly cutter is the first choice.

Regards

Martin

I am making some clamps for the machine vice which involves starting with a piece of steel 30mm by 20mm, reducing the smaller dimension to 18.8, and then creating wide rebates on two faces. I have tried mutliple passes of a 12mm cutter, which didn't turn out too well, and logic prompted the realisation that the cut in a single pass is the best way. The title gives my thinking, a fly cutter with a HSS tool will undoubtedly be a bit cheaper but the offside is the resharpening of the bit by grinding which I'm not good at. By contrast a carbide insert face mill will cost a bit more initially but there is a lot less grief to reach the end, however other views are always welcome to aid the decision making process, any thoughts?

Regards

Martin

I believe the Australian code may have come about due to the possibility of scale or sludge forming in passageways that could potentially impact on the gauge reading without the operators ability to clear all passageways by a blow through. A guess maybe but instinct suggests that may be right. What I do know from full size locomotive experience is how much the gauge glass reading can be altered from the true state by whether the regulator is open or not, it can be somewhat disconcerting to watch your half glass disappear into the bottom nut when you shut off.

Regards

Martin

I would add a cautionary tale about choice of carrier. I sold a quantity of 0 gauge rail to a gentleman in the Republic of Ireland, and since I wanted to keep the shipping costs in line with the value of the goods I used P2G who subcontracted the move to Hermes. Suffice it to say, the last I saw of it was at the pick up shop where I left it, the purchaser has yet to see it. It then took me 5 months of wrangling with P2G to get my £36 recompense for their and Hermes total failure. I would never use either of these ever again.

By contrast when I sold the SX2P to Ron Laden, the crate was uplifted at the agreed time and delivered to him the next day in proper order for under £40. I used TNT who did exactly what they said they would do. It appears it's not necessarily even about the cost.

Regards

Martin

Ken

I would suggest which, is an almost impossible question to answer by anyone other than yourself, since I can't imagine anyone has experience of all three. Colours to the mast, I have an SX2.7 which I am very pleased with, I looked at the L variant and decided I didn't need it, and thus far I haven't. Both The SPG and Amadeal machines look to be essentially the same, and marginally larger than the Sieg, although whether this tranlates to greater capacity is moot. They both appear to have a 2 speed arrangement for the belt drive which possibly means better torque at low speed though this hasn't caused me any problem. They also seem to have some sort of tilting head which personally I wouldn't want at all, having gone to great lengths to tram the head, to voluntarily disturb this seems perverse, as well as having to do it all again.

R8 is certainly the better choice, all things being equal, and whilst I and others are full of praise for the service from Arc, I have no reason to believe the other two suppliers would be any less satisfactory. All the above is likely useless in helping you make a choice, good luck with it.

Regards

Martin

Made a new bench for the lathe. The table it's currently on is too low, causing backache if nothing worse, however I was reluctant to spend the time, money, or effort until I was happy the lathe would work ok, it seems to.

Dave/Jason

Some very useful info from both of you, thanks. The lathe is an SC3 so I feel I need to be a bit prudent with DOC, and while I suppose that 20thou would work, anymore might be pushing the rigidity of the toolpost assy. I think that Dave's point about v small increments possible with HSS is valid and there seems to be a case for using carbide initially and finishing with HSS if finish or tolerance is critical. Regarding oil I was coating the surface to be cut, rather than dabbing on as the cut progressed so I don't think I would shock it, certainly I felt the cut was "better", but there is obviously some furthe experimentation reqd on my part.

As a follow up to the job itself, using the PCD function on the mill DRO positioned the holes exactly right and even the counterboring went sweetly, any way the chuck fits nicely. I measured the spindle register radial runout which is 0.5 thou. With the wholly unscientifc use of a drill bit in the chuck, the roundest round thing I can easily lay my hands on, I'm getting 2 thou runout, which is perfectly adequate for wee steam engines, and my lack of ability to improve it means I'll have to accept it eitherway. Whether the runout is occurring in the backplate or the chuck itself I don't know, nor really care. It's perfectly usable and best of all the out of balance vibration has disappeared. Result Martin 1 China 0, for a change.

Regards

Martin

I could I suppose have looked up Tubal Cain before I started which would have been sensible, he recommends for BMS at 4" dia 135rpm, with a 50% -75% increase for carbide, so say a max of 250rpm, which does make my 800rpm somewhat high. As Dave has pointed out speed has a major impact on surface finish, my limited attempts have shown this to be so, and when I was doing it there seemed to be no difficulty in removing metal, nor were there nasty noises. It did generate a fair amount of heat and at that speed I suspect the insert life might be shorter than it need be, I'll put that down to learning. Has anyone any thoughts about cutting oil, my reading on the subject suggests either flood cooling or dry. I have another backplate to do in due course so I will try that at a lower speed.

Regards

Martin

NDIY

Sufficient and not too much are what I did for the (depth) protrusion, I agree that the radial accuracy is most important, which is what I meant by maybe half a thou light, I'll see when it's finished.

Regards

Martin

Edited By Martin Shaw 1 on 24/03/2019 12:02:31

Thanks for the thoughts chaps, although I fear I may have inadvertently misled you, for which I apologise. What you can't see on the other side of the backplate is the recess for the spindle register, so the backplate was mounted on the lathe when I turned the chuck register. The need to check the runout stems from a whole lot of other conditions that arose from when I first obtained the lathe. Todays job is to mark out and drill the chuck mounting holes, after which I should be good to go.

regards

Martin

I have been putting this off, for fear of my own limitations, however I have now turned the register. It was also the first time using carbide insert tooling which was also causing undue trepidation. Here is the result.

I am pretty pleased with how its turned out, sorry, but the surface finish is smooth, not perhaps to HSS finish but perfectly satisfactory for the application and the register is at 90 deg, to the right depth and whilst possibly half a thou under, the chuck is a snug fit. For the record it was turned at 800 rpm with a 10thou DOC, I was going carefully but I reckon you could double that confortably. Apart from the smoke I don't know whether cutting oil is beneficial, but the swarf was coming off in long unbroken twists suitably blued by the heat, I certainly didn't appreciate just how hot. It obviously requires drilling and once on the machine I'll check the runout, but whilst contemplating the next step I was struggling to see in my mind how all the holes were to be accommodated, until I worked out that 13.5 divided by 2 is 6.75 not 7.75. Bit of a basic error, I blame age. Thus far so good, it can't last.

Regards

Martin